The invention relates to a reproducing apparatus for a rotatable disc-shaped record carrier on which information signals are stored in spiral tracks. A scanning device for scanning the tracks, is arranged on a slide which is movable in a radial direction, by a motor via a gear mechanism to position the scanning device between an innermost position and an outermost position. The gear mechanism includes a pinion and two juxtaposed gear racks which are slidably guided parallel to one another, and which are tensioned relative to each other by means of a spring. One the gear racks is fixedly connected to the slide and a stop which is fixedly connected to the gear rack abuts a fixed stop on the apparatus when the scanning device is set to one of the positions.
In a commercially available apparatus for reproducing audio signals from a disc-shaped record carrier which can be scanned by a laser beam, generally referred to as a Compact Disc player, the pinion always remains in mesh with the two gear racks. When the slide abuts against the fixed stop on the apparatus the pinion is coupled to the gear rack, which is rigidly connected to the slide and, consequently, a positive coupling exists between the pinion and the slide. Control signals are stored in a narrow inner track area of the record, the audio signals are basically stored in a broad central track area, and control signals are stored in a narrow outer track area. The slide is driven to move the scanning device from the inner track area towards the outer track area and during normal operation, when the outer track area is reached but before the scanning device reaches the outer track, the scanning device is rapidly returned towards the inner track area by driving the slide in the opposite direction, after which the slide drive is switched off via a switch which can be actuated by the slide. In order to control the above switching process the slide-drive motor is connected to an electronic control circuit which at the beginning of a scanning operation starts the motor in a predetermined direction of rotation and which during normal operation, before the scanning device reaches the outer track, reverses the direction of rotation of the motor and switches the motor to a higher speed. If the direction of rotation of the motor is not reversed so that its direction of rotation remains the same, which occurs in the case of failure of the control circuit, the stop of the slide will abut against the fixed stop on the apparatus. The motor and the gear mechanism will then be overloaded due to positive coupling between the motor and the fixed stop, on so that these parts of the apparatus are likely to be damaged.